Field of the Invention
The present invention relates to an electrophotographic image forming apparatus such as a copying machine and a printer. The electrophotographic image forming apparatus (hereinafter referred to as an “image forming apparatus”) forms an image on a recording material, such as a sheet of paper, using an electrophotographic image forming method. The image forming apparatus may be, for example, a copying machine, a printer (a laser beam printer, a light-emitting diode (LED) printer, or the like), a facsimile apparatus, a word processor, or the like.
Description of the Related Art
First, by selectively emitting light to a photosensitive drum, which is an image bearing member uniformly charged by a charging device such as a charging roller, an image forming apparatus forms an electrostatic latent image on the photosensitive drum. The image forming apparatus then develops the electrostatic latent image to obtain a toner image by using a development device including a development roller and records the toner image by transferring the toner image onto a recording material. A cartridge removably attached to the image forming apparatus can be configured by integrating a photosensitive drum, a charging device, a development device, a cleaning device, and the like with one another. By using such a cartridge, it becomes easier to supply toner and replace or maintain various components that have reached their end of life, such as the photosensitive drum.
On the other hand, as a result of recent technological advances in extending lifespans of various components, toner containers require replacement more frequently than photosensitive drums or other components. A toner container, which needs to be replaced more frequently than other components, is therefore often separated from a cartridge.
If an image forming apparatus includes a plurality of cartridges, it needs to be detected, before an image is formed, whether all cartridges are correctly mounted on the image forming apparatus. If a toner cartridge is not mounted and an image is formed, toner is not supplied to a development device. In this case, a blank sheet might be output or, because of the lack of toner, friction between members will increase and a developer bearing member or the like might be damaged, thereby outputting a sheet on which vertical streaks are printed.
In Japanese Patent Laid-Open No. 1-263662, therefore, a nonvolatile memory is provided for each cartridge. Each nonvolatile memory is accessed at an arbitrary time in order to confirm that the corresponding cartridge is correctly mounted.
As another method, a configuration is known in which a mechanical lever sensor or an optical sensor is provided and the position of a switch changes when each cartridge is correctly mounted or when each cartridge is not mounted or is incorrectly mounted.
In the above example of the related art, however, a reading unit for a nonvolatile memory, a lever sensor, an optical sensor, or the like needs to be provided for the image forming apparatus, which undesirably increases the number of components and the cost.